Research on current distribution test of neutral-bus arresters multicolumn parallel connected in converter station

Once DC transmission line or pole bus-bar grounding fault occurs; the energy of neutral-bus arresters will be very great. So neutral-bus arresters are designed in type of multicolumn parallel. To avoid one column of the varistors assuming too much energy because of the current distribution inequality, the current distribution coefficient must be strictly controlled. The method of judging current distribution is to test the current distribution coefficient of the arrester at 500A under standard lightning and switching current. And compare it with 1.1 which met the requirements of national standard. However, the current amplitude and waveform of neutral-bus arresters in real fault conditions are so different. The current distribution characteristic may also be different. This article tested the current distribution, analyzed the influence of current amplitude and current type on current distribution characteristic. The results show that the current distribution coefficient decreases gradually, along with the increasing of impulse current ranging from 25A to 500A per column. The current type has no effect on the current distribution characteristics of valve multicolumn parallel at low current.